When water is to be pumped out of an outdoor pit or reservoir, it is important to prevent debris, such as leaves, sticks, discarded plastic and paper articles, stones, etc., from entering the pump. Rotary self-cleaning strainers that contain cylindrical screens for performing the straining function are often used for this purpose.
The strainer is attached to the end of a conduit and immersed in the body of water that is to be pumped. The pump is operated to suck water through the strainer and conduit, as the strainer screen prevents debris from being sucked into the conduit along with the water. Certain debris may adhere to the screen's exterior due to the pump suction force. However, the continued adherence of such debris to the screen's exterior, and resulting impairment of flow through the screen, is prevented by rotating the screen past a nozzle structure which is disposed on the interior of the screen and directs water outwardly through the screen to dislodge the debris. The water is fed under pressure to the strainer through a separate supply line which may be tapped into the pump's outlet. The water acts on only a limited circumferential zone of the screen at any given time to force adhering debris away from the exterior of the screen as the screen revolves past the nozzle structure. The remainder of the screen serves to conduct the flow of liquid that is being pumped out of the pit or reservoir through the screen and into the conduit.
The present invention relates to improvements in rotary self-cleaning strainers of this general type. The rotary self-cleaning strainer of this invention possesses a number of novel and unique features which individually and collectively contribute to the improvements. These features are disclosed in the preferred embodiment of the invention which will be illustrated and described herein. This embodiment of the invention comprises materials that are strong, lightweight and have a long working life. The organization and arrangement of the various component parts and the extensive use of such strong and lightweight materials contributes to a rugged and durable rotary self-cleaning strainer that possesses superior attributes over prior strainers of the same general type.
One feature of the disclosed preferred embodiment relates to the manner in which the screen is arranged for rotation, and this feature is characterized by novel means for journaling and sealing the rotary portion of the strainer to the non-rotary position.
A further aspect of the invention relates to a novel configuration in the non-rotary portion of the strainer that promotes a more substantially uniform flow velocity through the rotary screen over the zone of the screen that is not exposed to the self-cleaning action. In certain other rotary self-cleaning strainers already in use, there is a significant disparity in flow velocity through the screen at different locations on the screen. This gives rise to "hot spots" and hinders the overall effectiveness of the pumping action.
A still further feature of the invention relates to the manner in which the nozzle structure that performs the self-cleaning function is organized and arranged in assembly with other component parts and to impart rotation to the screen.
The foregoing features, advantages and benefits of the invention, along with additional ones, will be seen in the ensuing description and claims which should be considered in conjunction with the accompanying drawings. The drawings disclose a preferred embodiment of the invention in an exemplary usage according to the best mode contemplated at the present time in carrying out the invention.